Radiological aspects of fusion reactor safety: risk constraints in severe accidents

A methodology is proposed for determination of the constraints on severe accidents in lithium cooled fusion reactors, based on the potential hazards associated with such accidents. The method utilizes a probabilistic approach to risk calculation. The most effective mechanism for activation product release is found to be volatilization of structure as a result of lithium fires. Several factors were found to influence the consequence of lithium fires, most notably the reactor structural material type and total volume. It is concluded that the consequences of estimated maximum possible release from a properly designed fusion reactor are substantially less than the maximum light water reactor accident consequences